Heat exchanger pass separator construction



P. BIZZARRO 3,490,522

HEAT EXCHANGER PASS SEPARATOR CONSTRUCTION Jan. 20, 1970 Filed Feb. 20, 1968 Av d/avar- 3,490,522 Patented Jan. 20, 1970 United States Patent Oifice 3,490,522 HEAT EXCHANGER PASS SEPARATOR CONSTRUCTION Peter Bizzarro, Hazardville, Conn., assiguor to United Aircraft Corporatiom'East Hartford, Conn., a corporation of Delaware Filed Feb. 20, 1968, Ser. No. 706,931

Int. Cl. F28f 13/08 US. Cl. 165-166 3 Claims ABSTRACT THE DISCLOSURE BACKGROUND OF THE INVENTION A typical plate-fin heat exchanger is disclosed in Patent No. 3,196,942 issued toiK. R. Prentiss on July 27, 1965, which illustrates a multi-pass heat exchanger which utilizes a portion of the closure bar extending a short distance into the core as the onlymeans for preventing leakage or short circuiting between" adjacent passes. The primary use of the shortpiece closure bar at this point is to form a rigid side face for accommodating the pass header.

It is a well known expedient to prevent short circuiting or leakage between adjacent passes by extending this type of end closure bar to extend through the core and define a barrier between passes. Obviously, by running the pass separator the full length of the core, the fin sheets would have to be cut in sections to follow the path of each pass separator. This notionly results in a loss of heat transfer area but additionally, adds to the weight, manufacturing complexity and cost of the. heat exchanger. I have found that I can obviate this problem by inserting a bent tab made of very thin material whose height matches the height of the passage in a slot in the short pass separator closure bar piecewhich may run the {full length of the core in the fin channel. The finsv may be either straight through or wavy since the tab will be sufiiciently flexible to follow the sine waves defined by the fin corrugations.

SUMMARY OF INVENTION The primary object of this invention is to provide a thin, flexible, metal strip extending in the corrugations of fins of a plate-fin heat exchanger core to define a wall between passes formed therein.

Other features and advantages will beapparent from the specification and claims and from the accompanying drawings which illustrate an embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a view in perspective showing a multipass heat exchanger.

FIGURE 2 is an enlarged view in elevation with a fragmentary sectional view, and a view in phantom illustrating the invention.

FIGURE 3 is an enlarged sectional view showing the details of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1 which generally shows a heat exchanger indicated by numeral havinga core 12, low temperature fluid inlet header 14 and low temperature fluid exit header 16, high temperature inlet fluid header 18, high temperature fluid exit header 20 and turning headers 22 and 24. Suitable piping is connected to each of the headers for conducting fluid into core 12 and discharging fluid therefrom. In essence, this multi-pass crossflow heat exchanger passes flow through a series of passes formed in the core so'that hot air passes alternate with cold air passages for obtaining indirect heat transfer.

As is typical in a cross-flow plate-fin heat exchanger, the core is constructed by sandwiching corrugated fins between parallelly spaced plates and alternately orienting adjacent layers so that the? corrugations which form openended channels are 90. with respect to each "other. Closure bars are mounted at the side edges of the fins preventing the escapement of fluid. I

As shown in FIG. 2 a typical passage 28 of core 12 is formed by disposing fins. 30 between spaced plates 32 and 34. This fin extends toall sides of the core. The edges of the fin are sealed 03 by closure bar 36. Another closure bar (not shown) is mounted on the other edge of the fin. The fin, being corrugated, defines channels opened on each end that extend across the core. Header 20 communicates with one of these ends for distributing fluid through these channels which communicate with another header on the opposite end of the core.

The next adjacent layeris similarly constructed, however, fin 38 has the corrugation running 90 with respect to fin 30. As noted from FIG. 2, plate 34, the bottom wall of passage 28, forms the topwall of passage 40. A second plate 42 is parallely spaced from plate 34 defining the other wall of passage 40.- Closure bar 44 is mounted adacent the edge of fin 38. a

The other passages aresimilarly formed and the fins, plates and closure bars are stacked and bonded in any suitable manner such as brazing. A bottom and top plate complete the core.

A short piece of closure bar 46 (one being shown) is inserted at the junction points of adjacent passes formed in the passages as shown FIG. 1. Obviously, some of the fins are cut away to receive these elements.

In accordance with this-invention a tabi inserted into the side of element 46 is bent to run parallelly with the channels in that passage. The tab is a flat strip preferably made from thin flexible material and is sufficiently wide to'touch the adjacent plates and extends part way or completely through the core. This tab serves as a' pass separator to prevent fluid in adacent passes to intermingle.

Hence, for example, it can be appreciated from the foregoing that fluid admitted into header 18 passes through core .12 and into turning header 22Zwhere it is returned, for the second pass, to the core and passes there through to turning header 24 wherein again the fluid is passed through core 12 and discharged into the collection header 20 and out through the pipe attached thereto.

Obviously, the fluid in the passage 28 passes through various sections thereof three times. Pass ;,feparators may be mounted between each pass in the passage as desired.

FIGURE 3 more clearly shows the details of the tab (like reference. numerals refer to like parts in all the figures). The fin 3.0 (for example) is cut away sufliciently to receive the short piece closure bar 46 and the bent portion of tab. 50. A slot 52 is formed in one side of closure bar 46 to receive the end of tab 50. The other Itwill be obvious that the tab can be inserted in the end of closure bar member 46 if such is desirable. In either case the tab serves to prevent leakage through the gap .formed by the cutaway fin portion.

3 4 w I claim: a n a .f -4 sai'dr pass separatorjextending. rearwardly from said 1. A heat exchanger of the type that has a core inmember and into the spaced defined by adjacent high cluding a plurality of stacked parallelly spaced flat plates, and low points of said corrugated fins.

corrugated fins defining high and low points sand- 2. A heat exchanger as claimed in cliam 1 wherein said wiched between the plates terminating at the face of 5 pass separator includes a flat-like flexible member. core and defining open-ended channels, the corru- 3. A heat exchanger as claimed in claim 2 wherein gated fins in alternate adjacent layers vbeing oriented said flexible member is substantially as high as the space 90 relative to the corrugated fins in said adjacent between adjacent flat plates.

layers, a header attached to the face of the core for directing 10 References Cited the flow of heat transfer medium atleast back UNITED STATES PATENTS and forth in at leastone of said layers, a member extending part way into said core and having a 1,635,838 7/1927 l' surface aligning with the face of the core so as to 3,196,942 7/1965 Prentlss 165166 provide a welding surface for the header, a pass 15 3,262,496 7/1966 Bawabe 165-166 separator attached to said member extending into 3 0 517 19 Butt the core so as to provide a barrier between the junc- I ture WhCI'C the flOW gOCS back and fOI'th in said i y Examiner layer, said pass separator being thinner relative to the v space between the high and low points of said cor- 20 T. W. STREULE, Assistant Examiner rugated fins, 

